I also had this postinstall-loop-problem in my Raspberry Pi 5 when I used the Yunohost image. The solution was to first install Raspberry Pi OS and then Yunohost on top according to the instructions “dedicated server with Debian 12”. Install YunoHost | Yunohost Documentation
I used the official 64bit Raspberry Pi OS without the desktop, as you wouldn’t see it anyway. Then I followed the instructions from Yunohost - with the post-installation via the command line.
Maybe this helps some of you.
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